A recent study from Northwestern Medicine explains that “exposure to even moderate ambient lighting during nighttime sleep, compared to sleeping in a dimly lit room, harms your cardiovascular function during sleep and increases your insulin resistance the following morning.” In fact, the researchers found that even just one night of sleeping in a room with moderate light can “impair glucose and cardiovascular regulation” which may increase your risk of heart disease, diabetes, and metabolic syndrome. This happens because when you are exposed to light, even during the day, our sympathetic nervous system is activated and our heart rate increases. Sleep is the time when our parasympathetic nervous system should be activated in order to restore our bodies. The solution? Blackout curtains or a good quality eye mask.